Technical Field
The present disclosure relates to integrated sensor devices. The present disclosure relates more particularly to integrated fluid sensors.
Description of the Related Art
Fluid injection systems are utilized in a large variety of applications. Such applications include medical applications, wherein infusion pumps, syringe pumps, auto-injectors, and many other types of devices deliver fluid to a patient. Often, a particular flow rate is desired for delivery of the fluid. For instance, medication or drugs delivered intravenously to a patient during surgery or post-surgery typically are delivered in very precise doses. Delivering an incorrect dose can lead to serious injury or even death. In one common technique for monitoring the flow rate of a drug in an infusion pump, a stepper motor which forces liquid from a reservoir through a feed line to the patient is monitored and displacement of the fluid is calculated based on displacement of the stepper motor. However, such a method for monitoring the flow rate has drawbacks in that it often does not take into account volumetric chamber irregularities, temperature fluctuations, fluid viscosity, atmospheric pressure and back pressure variability. Any error in calculating the flow rate can be very harmful to the patient.
Current infusion pumps, syringe pumps, and auto-injectors lack true closed-loop feedback, like a flow sensor, to ensure that the correct dose size and flow rate are administered for any particular drug. These devices often rely instead on calculations for dose size and flow rate data derived from drip sensors for gravity-based pumps and screw/piston position sensors or load cells used in volumetric pumps. These flow rate and dose size calculation methods are subject to inherent errors introduced by volumetric chamber irregularities, temperature, fluid viscosity, atmospheric pressure, and back pressure variability. Additionally, and perhaps most critically, there is the potentially fatal human error of administering the wrong drug.